In automatic welding systems of the type herein referred to, a welding carriage travels about the pipe on a track which encircles the pipe and which is spaced from the outer pipe surface over its periphery. The track is located at a predetermined uniform distance from the pipe end, and the welding apparatus carried by the welding carriage is disposed to weld at the joint between the pipe end and the end of another section of pipe aligned and closely spaced therefrom. Since the welding of pipe lengths together in the field requires that the welding be done quickly in order to be economical, it is necessary that the track be positioned spaced from the pipe end and latched in place very rapidly and accurately. The track may be spaced from the pipe end by hand through use of a ruler, and a number of locator devices for this purpose have been developed and some are still in use, although none are entirely satisfactory. Hand locating of the track is not very rapid, and adds to the cost of welding. When a pipe is welded to another pipe, the pipe at the location of the track becomes heated, and the pipe consequently expands. The resiliency provided by the slotted crossbars of the track structure herein disclosed allows pipe expansion without breakage of the latch connecting the track ends. Therefore, the pipe can expand when hot and contract when cool without disturbing the track mounted thereon. This invention is designed to provide an improved track structure and to provide an improved track locating means whereby the track is more dependable in use and whereby the track may be more rapidly installed.